48 PHILOSOPHICAL TKANSACTIONS. [aNNO 17QI. 



there is no heaving and no blue flame the mass is sensibly cooler, and only of a 

 dull red heat, l'' 20"" workman observes, that the metal sticks less to his tools. 

 Pig-iron he says fastens on it immediately, and must be shaken off" by striking 

 the other end with a hammer ; as it approaches more and more towards nature 

 (malleable iron) it adheres less ; and when the tools come clear up out of the 

 mass, he judges it to be fermented enough, l"^ 23'" little heaving or blue 

 flame ; metal stifFer, and of a dull red ; flame turned on and soon off again. 

 1*' 26'" by constant stirring the metal is become as fine as sand. Workman re- 

 marks, that the flame, which re-appears over the whole mass, looks more 

 kindly. It is evidently of a lighter blue colour, li'' flame turned on and soon 

 oft' again. Mass ferments strongly. Hissing noise heard : this noise was dis- 

 tinguishable in some degree ever since the blue flame and heaving motion be- 

 came visible, but always faint till now. l'' 40"^ less blue flame, l'' 48"^ flame 

 twice turned on and off' in this interval. Metal now clots, stands wherever it 

 is placed, without any tendency to flow, and no liquid pig iron now remains in 

 the bason of the furnace ; the mass has been constantly stirred and turned over, 

 l'' 50"" a little finery cinder appears boiling up amid the mass. Workman attri- 

 butes the increase of the hissing to this, l'' 53'" scarce any perceptible blue 

 flame or heaving. All the metal is now gathered into lumps, which the work- 

 man beats and presses with a heavy-headed tool. He brings them successively 

 into the hottest part of the furnace, into which the flame has been admitted. 

 He now stops the port hole in the door at which he had introduced his tools, 

 and applies a fierce flame for G or 8 minutes ; the metal is then rolled. 



These appearances, at least the most interesting of them, seem to admit of 

 an easy explanation ; and Dr. B. offers the following observations, as sui)ple- 

 mental to those for which we are already indebted to the Swedish and French 

 chemists on this important branch of metallurgy. He assumes the following 

 propositions as already proved by these philosophers. 1 . That cast iron is iron 

 imperfectly reduced, or, in other words, that it contains a portion of the basis 

 of vital air, the oxygene of M. Lavoisier. 2. That it contains a portion of 

 plumbago, with which grey cast iron most abounds. 3. That plumbago consists 

 of iron united to charcoal. 4. That fixed air, which he would rather call car- 

 bonic acid air, consists of oxygene and the constituent parts of charcoal. 



The heaving or swelling motion, so conspicuous in the process, is doubtless 

 owing to the discharge of an elastic fluid ; and the lambent deep blue flame, 

 breaking out in spots oVer the whole surface, shows that this elastic fluid is an 

 inflammable gas of the heavy kind. That no doubt might be left on the former 

 of these circumstances. Dr. B. directed the workman to take out, at 2 different 

 periods, a quantity of the metal where it was working most sti-ongly. Both 

 proved, on examination, to be spungy, cellular, and full of bladder holes. 



